Florfenicol is a broad spectrum antibiotic of Formula I

It has wide spread application in veterinary medicine for the treatment of both Gram positive and Gram negative bacteria as well as rickettsial infections. Florfenicol is also known as [R-(R*,S*)]-2,2-Dichloro-N-[1-(fluoromethyl)-2-hydroxy-2-[4-(methylsulfonyl)phenyl]ethyl]acetamide.
Commonly-assigned U.S. Pat. No. 5,663,361, the disclosure of which is incorporated herein by reference, describes the synthesis of Florfenicol intermediates and their use in processes for making Florfenicol. The primary advantage discussed therein is that the process eliminated the prior art's requirement to isolate the aminodiol sulfone (ADS) from the reaction vessel before proceeding with the Florfenicol synthesis.
More recently, U.S. Patent 2005/0075506 A1 described a process for preparing a compound of Formula II that is useful as an intermediate in the synthesis of Florfenicol.

The process called for reacting the hydrochloride salt of an optically pure aminodiol compound of Formula III with acetone followed by acetyl chloride to give a compound of Formula II. The compound of Formula II is then reacted further to give Florfenicol of Formula I.
A major drawback of the process disclosed in 2005/0075506 A1 is the use of the aminodiol starting material of Formula III. The aminodiol compound of Formula III is expensive. It is also difficult to isolate and handle due to its amphoteric nature.
The present invention addresses this shortcoming and provides a still further alternative method of preparing useful intermediates included in the synthesis of Florfenicol.